AuSn Preform Thickness’s Effect on Thermal Management in Semiconductor Laser Applications

Abstract

For the plethora of applications that require a high-melting die-attach solder, 80Au/20Sn is a great choice to ensure good performance and reliability, especially when used in one of its most highly demanded applications: semiconductor laser die-attach. However, difficulty managing thermal heat transfer has prevented the widespread use of semiconductor lasers. When the operational heat of these devices increases, their longevity and potential become limited. One option to improve thermal transfer is to use a thinner 80Au/20Sn preform in the bondline, which allows the heat to transfer to the heat-sink more quickly and efficiently. The creation of voiding hot spots—due to the lack of solder volume—is a perceived concern when using a thinner preform in the solder joint, which then contradicts the original intention. Voiding percentages were defined for several 80Au/20Sn preform thicknesses—ranging from 0.002″ to 0.00035″ thick—allowing for conclusions to be drawn on the effect of 80Au/20Sn preform thickness on thermal transfer in semiconductor laser technologies.